Case Report: Efgartigimod as an additional therapy for MOG antibody-associated disease overlapping GFAP-IgG.

Introduction: Myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease (MOGAD) and autoimmune glial fibrillary acidic protein (GFAP) astrocytopathy have received increasing attention in recent years. However, the coexistence of anti-MOG and anti-GFAP antibodies has rarely been reported. Case: A 53-year-old man presented with a headache, slow reaction, nonsense talk, unsteady walking without diplopia or decreased vision. Lumbar puncture revealed the presence of anti-MOG and anti-GFAP antibodies in the cerebrospinal fluid. Magnetic resonance imaging revealed multiple high signal intensities in the white matter. The patient was diagnosed with MOGAD syndrome with overlapping GFAP-IgG. Treatment comprised high-dose methylprednisolone and efgartigimod therapy, followed by gradual tapering of oral prednisolone and the addition of an immunosuppressant, leading to symptomatic improvement and sustained remission. Conclusion: We report a case of MOGAD-overlapping GFAP IgG treated with combination therapy of steroids and efgartigimod. This case enhances our understanding of the clinical manifestations of overlapping syndromes and expands the treatment options for this disorder.